Fix creating top menu entry for serviceuser plugin

Change-Id: Iefadde34cbe2d7e1899dd9afe63e7a4cd6beaa70
diff --git a/src/main/java/com/googlesource/gerrit/plugins/serviceuser/Module.java b/src/main/java/com/googlesource/gerrit/plugins/serviceuser/Module.java
index 89510bb..5b5df2f 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/serviceuser/Module.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/serviceuser/Module.java
@@ -25,6 +25,7 @@
 import com.google.gerrit.extensions.registration.DynamicMap;
 import com.google.gerrit.extensions.registration.DynamicSet;
 import com.google.gerrit.extensions.restapi.RestApiModule;
+import com.google.gerrit.extensions.webui.TopMenu;
 import com.google.gerrit.server.git.validators.CommitValidationListener;
 import com.google.gerrit.server.project.ProjectLevelConfig;
 import com.google.inject.AbstractModule;
@@ -38,6 +39,7 @@
     bind(CapabilityDefinition.class)
         .annotatedWith(Exports.named(CreateServiceUserCapability.ID))
         .to(CreateServiceUserCapability.class);
+    DynamicSet.bind(binder(), TopMenu.class).to(ServiceUserTopMenu.class);
     DynamicSet.bind(binder(), GitReferenceUpdatedListener.class).to(RefUpdateListener.class);
     DynamicSet.bind(binder(), CommitValidationListener.class).to(ValidateServiceUserCommits.class);
     install(new FactoryModuleBuilder().build(CreateServiceUserNotes.Factory.class));
diff --git a/src/main/java/com/googlesource/gerrit/plugins/serviceuser/ServiceUserTopMenu.java b/src/main/java/com/googlesource/gerrit/plugins/serviceuser/ServiceUserTopMenu.java
new file mode 100644
index 0000000..eb2606d
--- /dev/null
+++ b/src/main/java/com/googlesource/gerrit/plugins/serviceuser/ServiceUserTopMenu.java
@@ -0,0 +1,75 @@
+// Copyright (C) 2022 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.googlesource.gerrit.plugins.serviceuser;
+
+import com.google.common.collect.Lists;
+import com.google.common.flogger.FluentLogger;
+import com.google.gerrit.extensions.annotations.PluginName;
+import com.google.gerrit.extensions.annotations.RequiresCapability;
+import com.google.gerrit.extensions.api.access.PluginPermission;
+import com.google.gerrit.extensions.client.MenuItem;
+import com.google.gerrit.extensions.webui.TopMenu;
+import com.google.gerrit.server.CurrentUser;
+import com.google.gerrit.server.permissions.PermissionBackend;
+import com.google.gerrit.server.permissions.PermissionBackendException;
+import com.google.inject.Inject;
+import com.google.inject.Provider;
+import java.util.ArrayList;
+import java.util.List;
+
+@RequiresCapability("printHello")
+public class ServiceUserTopMenu implements TopMenu {
+  private static final FluentLogger logger = FluentLogger.forEnclosingClass();
+  private final String pluginName;
+  private final Provider<CurrentUser> userProvider;
+  private final List<MenuEntry> menuEntries;
+  private final PermissionBackend permissionBackend;
+
+  @Inject
+  public ServiceUserTopMenu(
+      @PluginName String pluginName,
+      Provider<CurrentUser> userProvider,
+      PermissionBackend permissionBackend) {
+    this.pluginName = pluginName;
+    this.userProvider = userProvider;
+    this.permissionBackend = permissionBackend;
+    menuEntries = new ArrayList<>();
+
+    try {
+      if (canSeeMenuEntry()) {
+        menuEntries.add(
+            new MenuEntry(
+                "Browse",
+                Lists.newArrayList(new MenuItem("Service Users", "/x/serviceuser/list"))));
+      }
+    } catch (PermissionBackendException e) {
+      logger.atSevere().withCause(e).log("Unable to compute permissions.");
+    }
+  }
+
+  private boolean canSeeMenuEntry() throws PermissionBackendException {
+    if (userProvider.get().isIdentifiedUser()) {
+      return permissionBackend
+          .currentUser()
+          .test(new PluginPermission(pluginName, CreateServiceUserCapability.ID));
+    }
+    return false;
+  }
+
+  @Override
+  public List<MenuEntry> getEntries() {
+    return menuEntries;
+  }
+}